Underwater salvage operations by "Hard-hat" and "Scuba" divers typically necessitate the tiring and time consuming determination of the locus of the item to be recovered. Once found, salvage operations requiring much labor, such as carrying and attaching heavy, stiff hoisting cables to the salvage item, may be almost impossible due to the additional exertions of the diver and the concomitant use of breathing air. These factors severely limit the time a diver has to work on the project underwater.
An attempt to solve these problems is exemplified in U.S. Pat. No. 3,813,177, issued May 28, 1974 to Howard Cartwright for a "Recovery Cable Connector for Diver-swimmer", which is incorporated herein by reference. Briefly, the cable connector of Cartwright comprises an engageable male and female part. The female part may be shackled to the salvage item and the male part connected to floatation gear or a hoisting cable. A hauling line, of plaited nylon, attached to the male part, extends coaxially out its head and is threaded into its opening and over a sheave in the female so that hauling of the line causes the parts to be brought into union whereupon spring-loaded latches on the female part engage an enlarged head of the male part. When the two parts engage, spring-biased electrical contactors contact the female part closing an electrical circuit to thereby signal the engaged condition to a surface ship to begin hoisting or to cause actuation of an explosive valve to allow a pressurized fluid from a source to inflate the floatation gear and thus bring the salvage item to the surface.
The above apparatus of Cartwright suffers from several deficiencies. First, the explosive valve is limited to a one time use adding to the operational costs of the system. Second, inasmuch as the valve is classified as an explosive, it requires the expensive and hazardous use of a storage magazine. Third, presently available explosive valves do not readily and inexpensively meet the stringent non-magnetic requirements of present military specifications. The non-magnetic criterion may be crucial when the item to be salvaged is an unexploded ordnance which may be capable of being armed by even a slight change in its ambient magnetic field. The dangers in having magnetic equipment nearby to such ordnance can be readily seen. It would thus behoove a designer and user of salvage equipment to insure the use of non-magnetic materials in such equipment. Fourth, the explosive valve is controlled by a firing lead assembly which requires a small battery to provide power for actuation of the explosive valve. Fifth, to ensure proper and reliable actuation of the valve, the battery should not have been used previously nor should it have experienced very long shelf life. This can lead to waste. Sixth, since the apparatus of Cartwright is to be used underwater and invariably in ocean environments of high salinity, there is the omnipresent danger that leakage into the battery box may occur with a concomitant battery shorting potential. Finally, the use of a battery in Cartwright requires the use of electrical leads which are unprotected and subject to pulling, loosening, cutting and other underwater harzards thereby potentially reducing the reliability of the apparatus.